Structural Changes in the Aging Brain

Publisher Summary The phenomenon of aging is a part of a continuous developmental sequence commencing with embryogenesis and proceeding through a number of maturational phases during the life span of the organism. The process of aging exerts its effects on all organs of the body, and the brain is no exception. Some degree of loss of substance is the most obvious characteristic of the normal aging process, but the degree of alteration varies enormously among subjects. The unique combination of genetic and epigenetic factors each individual represents is powerfully reflected in brain structure and function. Indeed, the brain of a vigorous 80-year-old patient may show fewer changes than that of an individual 20 years his junior. This spectrum of age-related patterns is further enhanced by the range of dementing illnesses to which the individual is increasingly vulnerable as the course of life progresses. This chapter reviews some of these alterations. A broad range of age-related alterations occur from brain to brain in the structural matrix, just as there is marked variation in the degree of cognitive, motor, and psychosocial intactness among the aged. The chapter describes the structural characteristics of healthy aged brain tissue and describes how the latter contrasts with the manifestations of pathological aging.